Central vacuum cleaning systems are common in residential and commercial buildings. In the typical central vacuum system a motorized vacuum unit is located in a remote part of a building. Airtight piping connects the central motorized unit with a number of terminal inlets which are normally wall-mounted. A flexible vacuum hose, capable of accomodating a variety of vacuum heads, can then be inserted into the terminal inlet. Suction is provided at the vacuum head when the central unit is switched on. Any materials picked up by the suction at the vacuum head are then drawn back through the piping system into a retaining receptacle at the central unit.
For convenience, some vacuum systems are designed so that the motorized vacuum unit is activited upon the insertion of the flexible hose into the terminal inlet. Typically, the terminal inlets have a circular opening into which the end of the flexible vacuum hose can be inserted. These openings are normally free of threaded portions or other fastening means and the hose is held in place by a friction fit and by the suction provided by the motorized unit. Situated on the inside of the circular opening are two spaced apart electrical contacts protruding slightly inward. An electrical wire connects each contact to opposing sides of a relay switching device located in the central motorized unit such that when an electrical circuit is completed between the contacts, the vacuum motor will start. In systems with numerous terminal inlets, the contacts are wired in parallel so that electrically connecting the contacts in any one inlet will start the vacuum motor.
Normally the end of the flexible vacuum hose which is insertable into the terminal inlet is made of conductive material so as to complete the electrical circuit between the two contacts. In this manner the system can be switched on by inserting the hose into the terminal inlet. Alternatively, the terminal inlet may be covered with a flap and a switch may be connected to the flap such that lifting the flap activates the central motorized unit.
The above described system requires the installation of suitable vacuum piping and electrical wires which connect the central motorized unit with the terminal inlets. Currently piping is held in place through the use of wires or pipe clamps which secure the pipe to floor joists, wall studs and the like. Typically the electrical wire is run along side of the pipe and either held tight against the pipe with the use of wires, ties or tape, or, the wire may be strapped independently to the surface over which the pipe is run. These methods have a number of drawbacks. It is often difficult to attach the electric wires and it can be time consuming. Further, because the electrical system needs to be tested prior to completing the wiring, it is often necessary to string up the wires, test the circuits, then go back and secure the wires in place. Replacement of the wire is also difficult and time consuming as each strap, wire, tie, or taped connection must be removed. Securing the wire by one of these means also requires the use of additional materials thereby increasing the cost of the installation.